1. Field of the Invention
The present invention is generally directed to key operated locks, and more particularly to a lock assembly for a safety deposit box with a guard side passive lock and a patron side lock wherein the key can be removed from the guard side lock when in the locked or the unlocked position.
2. Description of the Related Art
Two key lock assemblies are known in the art and are commonly used for safety deposit boxes and the like. Such lock assemblies typically require an authorized person to first unlock the lock assembly using a first key. The authorized person uses a first key and places the lock components in an unsecured orientation that permits a second person to lock and unlock the lock assembly, if so desired, with a second key. If the first authorized person, such as a bank security guard, does not unsecure the assembly, the second authorized person, such as a bank patron that owns or rents the safety deposit box, cannot access the box utilizing their second key.
A conventional safety deposit box assembly requires a security guard or another authorized person to insert the first key into the first lock in order to unsecure a guard lock. Under conventional circumstances, the security guard key cannot be removed from the lock assembly after it is moved to the unsecured orientation. Therefore, the security guard must leave the key with the owner and the safety deposit box or must remain in the presence of the key during the entire time that the owner of the safety deposit box utilizes the box. If the security guard must leave the presence of the box owner, the security guard key is available to the box owner without supervision. If the security guard remains in the presence of the box owner during the time that the safety deposit box is being used, the security guard cannot perform other duties. This situation either raises security concerns or reduces the efficiency of the security guard.
It is therefore one object of the present invention to provide a guard side passive two key lock assembly for a safety deposit box that does not require the guard key to remain in the lock assembly when in an unsecured orientation. It is another object of the present invention to provide such a lock assembly that permits the guard key to be inserted into a guard side passive lock assembly to unsecure the assembly and then to be removed prior to insertion of a patron side key. It is another object of the present invention to provide such a lock assembly that permits constant supervision of the guard side key by permitting the key to remain in the presence of authorized personnel at all times. It is yet another object of the present invention to provide such a lock assembly that improves the job efficiency of security guard personnel by permitting the security guard personnel to unsecure a safety deposit box guard lock without requiring them to remain in the presence of the box owner during use of the safety deposit box.
These and other objects, features, and advantages are provided by a guard side passive two key lock assembly of the present invention. In one embodiment, a safety deposit box lock assembly includes a housing and a latch bolt carried by the housing. The latch bolt is moveable between a locked and an unlocked position relative to the housing. The lock assembly has a guard lock that is moveable by a guard key between an unsecured orientation permitting movement of the latch bolt to the unlocked position and a secured orientation prohibiting movement of the latch bolt to the unlocked position. The lock assembly also includes a patron lock that is moveable by a patron key between a latched orientation that moves the latch bolt to the locked position and an unlatched orientation that moves the latch bolt to the unlocked position. The patron lock is moveable to the unlatched orientation only when the guard lock is in the unsecured orientation. The guard key of the lock assembly can be inserted into and removed from the guard lock both when the guard lock is in the secured and the unsecured orientation.
In one embodiment, the lock assembly further comprises a pin extending upward from a portion of the latch bolt and at least one guard lock tumbler lever. A pin slot is formed in each guard lock tumbler lever wherein the pin slots align with one another and with the pin when the guard lock is in the unsecured orientation.
In one embodiment, the lock assembly also includes at least one guard lock tumbler lever and a cam surface on an edge of each guard lock tumbler lever. Each of the cam surfaces bears against a portion of the guard key when rotated to move each guard lock tumbler lever.
In one embodiment, the lock assembly includes a plurality of guard lock tumbler levels and a cam surface on an edge of each of the guard lock tumbler levers. Each cam surface has at least one notch that align with one another when the guard lock is in the unsecured orientation to permit insertion and removal of the guard key in the unsecured orientation.
In one embodiment, the lock assembly includes a terminus at one edge of each cam surface of each guard lock tumbler lever that align with one another when the guard lock is in the secured orientation to permit insertion and removal of the guard key in the secured orientation.
In one embodiment, the lock assembly also includes a bolt plate carrying the latch bolt and includes a guard key post passing through a slot in the bolt plate and arranged generally perpendicular to the plate. A key groove is formed along the longitudinal axis of the post that guides a portion of the guard key along the post when the key is inserted in the guard lock. The key groove aligns with each notch in each tumbler lever cam surface when the guard lock is in the unsecured orientation.
In one embodiment, the key groove of the guard key post is positioned beyond the terminus of each tumbler lever cam surface when the guard lock is in the secured orientation.
In one embodiment, the lock assembly also includes a plurality dummy tumbler levers that each have a perimeter surface that does not intersect with a path of the notches. In this manner, the dummy tumbler levels do not interfere with insertion and removal of the guard key when the guard lock is in any orientation.
In one embodiment, the lock assembly includes a plurality of the dummy levers each having a perimeter surface with a terminus that aligns with the terminus of each guard lock tumbler lever cam surface. In this manner, the dummy tumbler levels do not interfere with insertion and removal of the guard key when the guard lock is in any orientation.
In another embodiment of the invention, a safety deposit box lock assembly includes a housing and a bolt plate received in and moveable relative to the housing between a locked and an unlocked position. A latch bolt is carried by the bolt plate and extends from the side of the housing when the bolt plate is in the unlocked position and at least partially retracts into the housing when the bolt plate is in the unlocked position. The lock assembly also includes a guard key opening in a face of the housing that is adapted to receive a guard key therein. The lock assembly includes a guard lock that is actuated by rotating the guard key when inserted in the guard key opening. The guard lock permits movement of the bolt plate to the unlocked position when in a unsecured orientation and prohibits movement of the bolt plate to the unlocked position when in a secured orientation. The lock assembly also includes a patron key opening in the face of the housing that is adapted to receive a patron key therein. A patron lock is actuated by rotating the patron key when inserted in the patron key opening. The patron lock moves of the bolt plate to the unlocked position only when the guard lock is in the unsecured orientation and when the patron lock is moved to an unlatched orientation. The guard key can be inserted into and removed from the guard key opening both when the guard lock assembly is in the secured and in the unsecured orientation.